Abstract: An impeller pump for moving large volumes of liquid against heads of up to 1 meteris formed by a substantial circular housing having its axis substantially vertical in which an impeller is mounted for rotation on the central axis. The impeller has an maximum diameter substantially equal to the inside diameter of the housing and is formed with a hub and the plurality of blades symmetrically positioned around the hub. Each blade extends radially outward of the hub from a root to a tip and has a foil shaped cross section with a lift to drag ratio at least 75 to 1 at a Reynolds number of under 10.sup.6. Each of the blades is skewed rearward in the direction of blade rotation so that the apparent aspect ratio of blade is increased and to reduce operating noise. Each blade has an angle of attack of between 2.degree. and 6.degree. and has a rake in the direction of flow through the impeller of between 3.degree. and 7.degree.. The impeller lifts water through the housing and directs it into the fish farm.